Before you start, write one sentence which fully describes your topic. Now underline 2-4 important words. These underlined words will be your key words. You will use them repeatedly in online research.

Example: I will examine the effect of volcano eruptions on our weather.

Note: Don't use such common words as "of" or "on" as key words. They will make your search too big.

Do you know the basic facts about your topic?
What you might need to know:
Definitions of all the words
What period of history are we talking about?
Who were the important contributors to my field of study?
How does my topic fit in with other similar topics?

If not, go to an encyclopedia to read up on it a little.
Or try an online encyclopedia. Or both.

Hint: This step is especially important if you need to finish your work before you can get to the library to find a book.

Now look to see if there is a book in the library that will help you. The best time to use a book is when you want an overview, or a lot of information on one topic. A book can give you an introduction and a whole lot more.

Now look for articles from magazines. The best time to use an article is when you want to look at one particular aspect of your topic. Sometimes a really good article can also give you the overview just like a book does.